Portable lamp



FIG. 1 is a perspective view of a portable lamp showing a new design;

FIG. 2 is a top view thereof; and,

FIG. 3 is a side view thereof, the opposite view being a mirror image thereto.

The broken line showing is included for the purpose of illustrating only and forms no part of the claimed design. 

The ornamental design for a portable lamp, as shown and described. 